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1985 K100RS throttle cable

I wish to replace the sticky throttle cable on my 1985 K100RS. I checked an on-line parts fiche and discovered there are two sizes offered: 969mm and 937mm. All 1985 K100RS models have the same handle bars, so how do I know which length to order?
I don't want to remove the cable and measure it, as it would essentially put my bike out of service until I receive the (back ordered) new cable.

I would have your VIN, know if you have any bar-backs or not, etc, then call one of the tool free BMW dealer phones and have them tell you which it is you need. The longer sounds like it would more than likely be for the Standard or the RT.

There was a recall on the throttle cable on your motorcycle. If your bike's throttle cable has it's adjuster several inches from the control, instead of at it, you need the throttle cable update parts, as well as this cable: 32 73 1 457 015 (the one described as 937mm). As I recall, if you use the longer cable, you can not adjust the free play correctly.

K100rs throttle cable

Thanks for the info re the recall. I paid a visit to the local BMW dealer, and he mentioned not a word about a recall. Somewhere on the WWW I saw a collection of all the BMW recalls or modifications published. I can't find it now. Anyone have a clue? TIA

It may have been a "service action" rather than a recall. It's been a long time. BMW (and, I assume, other manufacturers) has declared many of the ollder recalls "completed", having acheived some percentage of recalls performed vs number of units sold.

No - it WAS a recall, and yes - recalls never expire. The dealer probably wasn't in business around 1986 when the recall came out, but the reason for it was - the rubber mounted bars on the RT didn't have an adequate ground to the bars, and the throttle cable was working as the ground. That apparently could cause the cable to heat up due to the current flowing through it - causing it to bind and people to crash.

I'd look at the NHTSA website - they have listings of recalls, and I think they go that far back. The cable, installation, replacement bracket should be free IF it hasn't been changed already. You may have to contact BMW-Motorad US to have them inform the dealer that the recall is still (and always will be) in effect.

BTW - an original recall attempted to fix the problem by adding a heavy ground connection to the bars. That didn't seem to work. The final cable design isolated the bottom fitting using a plastic bushing from the engine, leaving no path to ground through the cable. That combined with the new ground connection did work.

Thanks for the detailed explanation, Don. I wondered what that ground cable was for.

So if Walt's accelerator cable has the plastic bushing on the throttle body side, he's already got an updated cable.

FYI - I had a sticky cable there a while back. I found that the teflon liner sleeve which separates the actual metal cable from the cable housing was protruding too much from the throttle body end and was getting caught in the curved throttle body lever, thus preventing the lever from moving freely. I removed the cable and was able to slip the sleeve back in, but I replaced the cable with a new one just to be safe.

Thanks for the detailed explanation, Don. I wondered what that ground cable was for.

So if Walt's accelerator cable has the plastic bushing on the throttle body side, he's already got an updated cable.

Basically yes. They did one other try with the cable at one point, but it was basically just moving the adjuster from mid-cable up to the grip assembly. The plastic bushing on the bottom end at the TB is a big clue. That requires replacement of the bracket on the back of the TB also to fit the bushing.

FYI - I had a sticky cable there a while back. I found that the teflon linersleeve which separates the actual metal cable from the cable housing was protruding too much from the throttle body end and was getting caught in the curved throttle body lever, thus preventing the lever from moving freely. I removed the cable and was able to slip the sleeve back in, but I replaced the cable with a new one just to be safe.

I've seen the sleeves move around a bit. Bet some crazy glue on the outside of the liner and shoving it back into the plastic sheath would also probably work in a pinch..

K100RS throttle cable

I returned to the dealer with some questions. My bike does has the updated throttle cable - reportedly identified by the location of the adjuster being near the throttle twist grip.
In a related matter, I also found the site with all (?) the service bulletins for your reading pleasure. It's here: http://k100rt.aforumfree.com/forum
Nice reference material that.

I returned to the dealer with some questions. My bike does has the updated throttle cable - reportedly identified by the location of the adjuster being near the throttle twist grip.
In a related matter, I also found the site with all (?) the service bulletins for your reading pleasure. It's here: http://k100rt.aforumfree.com/forum
Nice reference material that.

That cable could be try #1 by BMW, or the final solution.. You really have to check the bottom end of it (not easy to see, I used to remove the bottom of the airfilter housing to get to it) and see if the bracket with the plastic bushing is there. If it is - the recall has been done and BMW owes you nothing.

K100RS throttle cable

I picked up the new throttle cable today. It is identical to the one on the bike now, so I'm sure it's been updated. I installed the new one. Now the throttle is even more reluctant to return to the stop when the twist grip is released! Rats!
Darkness fell before I could do any more troubleshooting, so the problem is a mystery to me at this moment.
The cable is new, the toothed gear moves easily, the grease between the handlebar and the twist grip is relatively new (a few months old) and the rubber grip is not being fouled by the bar end weight.
Nothing is easy....
On the bright side, the old cable was really ready for the trash bin.

Does it return? If not, something in the throttle bodies is causing the problem.

If it does, something in the cable or grip is the problem (do you have the throttle friction screw?).

Disconnect the cable from the grip and actuate the cable. If it returns the problem is in the grip (I did mention the friction screw). If it doesn't, the problem is in the routing or tying down of the cable.